add app icon, file list menu control

main.go

@@ -19,6 +19,11 @@ import (
 //go:embed noise.png
 var noise []byte
 
+// this is the app icon
+//
+//go:embed icon.png
+var icon []byte
+
 var validFileTypes = []tk.FileType{
 	{TypeName: "BMP", Extensions: []string{".bmp"}},
 	{TypeName: "JPEG", Extensions: []string{".jpg", ".jpeg"}},
@@ -137,11 +142,53 @@ func main() {
 
 	menubar := tk.Menu()
 	fileMenu := menubar.Menu()
-	fileMenu.AddCommand(tk.Lbl("Open File"), tk.Underline(0), tk.Accelerator("Meta+O"), tk.Command(newFileInDirectory(img)))
-	fileMenu.AddCommand(tk.Lbl("Open Directory"), tk.Underline(0), tk.Command(newDirectory(img)))
+	fileMenu.AddCommand(tk.Lbl("Open File"), tk.Accelerator("Meta+O"), tk.Command(newFileInDirectory(img)))
+	fileMenu.AddCommand(tk.Lbl("Open Directory"), tk.Command(newDirectory(img)))
+	fileMenu.AddSeparator()
+	checkbox := fileMenu.AddCheckbutton(tk.Lbl("Show Filelist"))
+	bindVar := tk.Variable("FileList")
+	fileMenu.EntryConfigure(checkbox, bindVar)
 	menubar.AddCascade(tk.Lbl("File"), tk.Underline(0), tk.Mnu(fileMenu))
 	tk.App.Configure(tk.Mnu(menubar))
 
+	destroyFileList := func(destroy bool) {
+		if destroy {
+			tk.Destroy(fileList)
+		}
+		fileList = nil
+		lb = nil
+		bindVar.Set("0")
+	}
+	constructFileList := func() {
+		fileList = tk.Toplevel()
+		fileList.WmTitle("Files")
+		lb = fileList.Listbox(tk.Height(0))
+		for i := range directoryState.images {
+			lb.Insert("end", directoryState.images[i])
+			if i == slices.Index(directoryState.images, directoryState.currentFile) {
+				lb.SelectionSet(i)
+			}
+		}
+		tk.Pack(lb)
+		tk.Bind(lb, "<<ListboxSelect>>", tk.Command(func() {
+			selection := lb.Curselection()
+			updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[selection[0]]), img)
+		}))
+		tk.Bind(fileList, "<Destroy>", tk.Command(func(e *tk.Event) {
+			// list closed by user click on <x>
+			destroyFileList(false)
+		}))
+		bindVar.Set("1")
+	}
+
+	tk.Bind(fileMenu, "<<MenuSelect>>", tk.Command(func() {
+		if bindVar.Get() == "1" && fileList == nil {
+			constructFileList()
+		} else if bindVar.Get() == "0" && fileList != nil {
+			destroyFileList(true)
+		}
+	}))
+
 	// TODO: if someone presses the Meta key again after the openfile dialog box closes,
 	// it triggers a _release_ event instead of a press event. The second time afterward, it works correctly.
 	tk.Bind(tk.App, "<KeyPress>", tk.Command(func(e *tk.Event) {
@@ -158,28 +205,10 @@ func main() {
 		case "a":
 			if metaActive {
 				if fileList == nil {
-					fileList = tk.Toplevel()
-					fileList.WmTitle("files")
-					lb = fileList.Listbox(tk.Height(0))
-					for i := range directoryState.images {
-						lb.Insert("end", directoryState.images[i])
-						if directoryState.currentFile == directoryState.images[i] {
-							lb.SelectionSet(i)
-						}
-					}
-					tk.Pack(lb)
-					tk.Bind(lb, "<<ListboxSelect>>", tk.Command(func() {
-						selection := lb.Curselection()
-						updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[selection[0]]), img)
-					}))
-					tk.Bind(fileList, "<Destroy>", tk.Command(func(e *tk.Event) {
-						// list closed by user click on <x>
-						fileList = nil
-						lb = nil
-					}))
+					constructFileList()
 				} else {
 					// list closed by Meta-a
-					tk.Destroy(fileList)
+					destroyFileList(true)
 				}
 			}
 		case "Up":
@@ -212,5 +241,6 @@ func main() {
 	// }))
 
 	tk.Pack(img)
+	tk.App.IconPhoto(tk.NewPhoto(tk.Data(icon)))
 	tk.App.Wait()
 }